Fourth dose of Pfizer vaccine protects medicos against COVID-19 hospitalizations and deaths: JAMA

Israel: In residents of long-term care facilities (LTCFs), the fourth dose of the Pfizer BioNTech (BNT162b2) COVID-19 vaccine was associated with high protection against COVID-19 hospitalizations and deaths during a surge associated with the Omicron variant, showed a study published in the JAMA Internal Medicine.

Long-term care facilities (LTCFs) provide a variety of services, both medical and personal care, to people who are unable to live independently. Elderly residents of these LTCFs are at greater risk of severe and fatal COVID-19, due to reduced immunity following vaccination with COVID-19 mRNA vaccines and rapid decline in the immune response after 2 vaccine doses.

The vaccination campaign with the third BNT162b2 dose among LTCF residents showed high vaccine uptake and rapid declines in the incidence of SARS-CoV-2 infection and COVID-19 hospitalizations. To control the substantial surge of the SARS-CoV-2 Omicron variant, the administration of a fourth BNT162b2 COVID-19 vaccine dose was approved for individuals 60 years or older who were vaccinated with a third dose 4 months previously or earlier. Nonetheless, the association between receipt of the fourth dose and protection against infection remains elusive.

A team of investigators led by Khitam Muhsen, Tel Aviv University, Tel Aviv, Israel tried to determine the association of the fourth BNT162b2 dose with protection against SARS-CoV-2–related infections, hospitalizations, and deaths during the Omicron surge in long-term care facility (LTCF) residents.

Investigators analyzed the data of 43 775 LTCF residents (mean [SD] age, 80.1 [9.4] years; 29 679 women [67.8%]) of whom 24 088 (55.0%) received the fourth dose and19 687 (45.0%) received third dose (4 months previously or earlier). The median follow-up time was 73 days (4-dose group: IQR, 6 days; 3-dose group: IQR, 56 days). Cumulative incidences of SARS-CoV-2 infections, hospitalizations, and deaths during the Omicron surge were set as the main outcomes.

Key findings of the study,

• More than 7 days post-vaccination with the fourth dose, SARS-CoV-2 infection was detected among 4058 fourth-dose vs 4370 third-dose recipients (cumulative incidence, 17.6% vs 24.9%).

• The corresponding incidences of hospitalizations for mild-to-moderate COVID-19, severe illness, and mortality were 0.9% and 2.8%, 0.5% and 1.5%, and 0.2% and 0.5%, respectively

• The adjusted protections were 34%, 64%, and 67%, against overall infection, hospitalizations for mild-to-moderate illness, and severe illness, respectively, and 72% against related deaths.

Investigators thus conclude that a receipt of a fourth BNT162b2 dose is strongly associated with increased protection against COVID-19 hospitalizations, severe disease, and deaths during the Omicron surge as compared to 3 doses administered 4 months previously or earlier among LTCF residents.

Investigators also observed the presence of moderate protection against overall SARS-CoV-2 infection among LTCF elderly residents.

Reference:

Muhsen K, Maimon N, Mizrahi AY, et al. Association of Receipt of the Fourth BNT162b2 Dose With Omicron Infection and COVID-19 Hospitalizations Among Residents of Long-term Care Facilities. JAMA Intern Med. Published online June 23, 2022. doi:10.1001/jamainternmed.2022.2658